Method for automatically controlling hydraulic opener

ABSTRACT

An automatic control method for a taphole opener for opening a taphole by giving impact and rotation to a drill unit holding a drilling rod and driving the drill unit forward and backward by a hydraulically driven feed motor, which method comprises the steps of; detecting the driving load in the form of detected hydraulic pressure, stopping the driving but maintaining the rotation when said detected pressure reaches an upper limit set value beyond which buckling may occur, and resuming the driving when said detected pressure falls to a lower limit set value or below. The drilling rod of the drills unit is prevented from buckling and idle hitting and a quicker taphole opening operation and enhanced accuracy of taphole depth can be obtained. Thus remote operation is made possible through the automation of the taphole opening work.

FIELD OF THE INVENTION

The present invention relates to a control method for an opener for ablast furnace taphole.

DESCRIPTION OF THE PRIOR ART

In the operation of a blast furnace to produce pig iron, a taphole isopened, using an opener, to tap hot metal from the furnace. JapaneseUnexamined Patent Publication No. 6-322420, for example, describes ataphole opener as shown in FIG. 4. According to the figure, the tapholeopener opens a taphole 6 of a blast furnace, using a drilling rod 2 heldby a drill unit 1, by giving impact and rotation to the drill unit 1,and drives the drill unit 1 forward and backward using a feed motor 5installed on a guide cell 3 and driven by hydraulic power supplied froma hydraulic unit 4. A pulse generator 7 is connected with the rotaryshaft of the feed motor 5. An arithmetical unit 9 is provided forcounting output pulses of the pulse generator 7 upon receiving a tappingcommencement signal. The driven distance of the drill unit 1 is countedby the pulse generator 7 in the form of the number of pulses, and thehydraulic pressure during the taphole opening operation is continuouslymonitored by a pressure gauge 8 to measure the depth of the taphole 6.

FIGS. 5(a) and 5(b) are flowcharts showing the control flow of theaforementioned taphole opener. Once the taphole opening operation begins(step 1), the pressure gauge detects hydraulic pressure (step 2).

The detected hydraulic pressure is input to the arithmetical unit, whichjudges whether the detected pressure B is equal to or higher than a setpressure A (step 3). If the detected pressure B is lower than the setpressure, the tip of the drilling rod has not reached a pluggingmaterial in the taphole and, then, the control flow returns to steps 1and 2 and the forward driving of the drilling rod is maintained untilthe tip of the rod reaches the plugging material in the taphole.

When the tip of the drilling rod hits the plugging material in thetaphole during the forward driving of the rod, the detected pressure Bexceeds the set pressure A and, at that time, the value of the positiondetected is set to zero (step 4) and the counting starts (see FIG. 5(a)).

The rod is driven forward under visual monitoring to determine whetherthe forward movement proceeds normally and whether any bend occurs inthe drilling rod (see FIG. 5(b)). In the meantime, the number of thepulses is accumulated, and when the taphole opening is completed, atapping commencement signal is turned on (step 6), the drilling depth ofthe taphole is calculated from the accumulated number of pulses (step7), and the calculated result is shown on the output (step 8).

In the above-mentioned taphole opener, however, the forward movementspeed of the drilling rod is controlled manually so that the rod may notbuckle and, for this reason, the control is imperfect when the hardnessand strength of the plugging material in the taphole change resulting inlarge drilling resistance. As a result, the drilling rod sometimessuffers bending and its tip tends to wear very rapidly.

In addition, since the impacts are also controlled manually, visuallymonitoring if the forward movement is sufficient, an impactor of thedrill unit sometimes hits idly when the resistance against the forwarddriving is small, resulting in shorter service life or damage to theequipment.

Further, after the commencement of the taphole drilling is detected,detection of the drill depth in the taphole and rapid increase in theforward driving speed are confirmed also visually, and thereforeaccurate measures may not always be taken due to a slow reaction time.

Further yet, since the taphole opening operation is one of the casthouse operations wherein the taphole opener is manually operated by aworker visually monitoring its forward movement speed, there is aproblem that work environment of the operator is hot, dangerous anddirty with much dust.

SUMMARY OF THE INVENTION

The present invention provides an automatic control method for ahydraulic taphole opener, whereby a drilling rod of a drill unit can beprevented from buckling and idle hitting, the taphole opening time canbe shorter, and taphole depth can be measured more accurately, makingremote operation possible through automatic operation of taphole openingwork to liberate workers from a foul work environment.

The gist of the present invention is as follows:

(1) An automatic control method for a hydraulic taphole opener foropening a taphole by giving impact and rotation to a drill unit holdinga drilling rod and driving the drill unit forward and backward by ahydraulically driven feed motor, which method comprises the steps of:

detecting the driving load in the form of detected hydraulic pressure;

stopping the driving but maintaining the rotation when said detectedpressure reaches an upper limit set value beyond which buckling mayoccur; and

resuming the driving when said detected pressure falls to a lower limitset value or below.

(2) An automatic control method for a hydraulic taphole opener foropening a taphole by giving impact and rotation to a drill unit holdinga drilling rod and driving the drill unit forward and backward by ahydraulically driven feed motor, which method comprises the steps of:

detecting the driving load in the form of detected hydraulic pressure;

maintaining the impact when said detected pressure is equal to or higherthan a set value to commence the impact; and

stopping the impact when said detected pressure is lower than said setvalue.

(3) An automatic control method for a hydraulic taphole opener foropening a taphole by giving impact and rotation to a drill unit holdinga drilling rod and driving the drill unit forward and backward by ahydraulically driven feed motor, which method comprises the steps of:

detecting the driving load in the form of detected pressure;

setting the count of position detection to zero when the detectedpressure exceeds an upper limit set value for detecting that the drillunit has reached a plugging material in the taphole, commencing positiondetection from this position, and calculating the depth of the taphole;

stopping the driving of the drilling rod when the taphole depthaccording to the position detection becomes equal to or deeper than aset value and the detected pressure becomes equal to or lower than alower limit set value for detecting that the taphole has beenperforated;

stopping the driving but maintaining the rotation when, during theforward driving of the drilling rod, said detected pressure reaches anupper limit set value beyond which buckling may occur; and

resuming the driving when said detected pressure falls to a lower limitset value or below.

(4) An automatic control method for a hydraulic taphole opener foropening a taphole by giving impact and rotation to a drill unit holdinga drilling rod and driving the drill unit forward and backward by ahydraulically driven feed motor, which method comprises the steps of:

detecting the driving load in the form of detected pressure;

setting the count of position detection to zero when the detectedpressure exceeds an upper limit set value for detecting that the drillunit has reached a plugging material in the taphole, commencing positiondetection from this position, and calculating the depth of the taphole;

stopping the driving of the drilling rod when the taphole depthaccording to the position detection becomes equal to or deeper than aset value and the detected pressure becomes equal to or lower than alower limit set value for detecting that the taphole has beenperforated;

maintaining the impact when, during the forward driving of the drillingrod, said detected pressure is equal to or higher than a set value tocommence the impacts; and

stopping the impact when said detected pressure is lower than said setvalue.

(5) An automatic control method for a hydraulic taphole opener foropening a taphole by giving impact and rotation to a drill unit holdinga drilling rod and driving the drill unit forward and backward by ahydraulically driven feed motor, which method comprises the steps of:

detecting the driving load in the form of detected pressure;

setting the count of position detection to zero when the detectedpressure exceeds an upper limit set value for detecting that the drillunit has reached a plugging material in the taphole, commencing positiondetection from this position, and calculating the depth of the taphole;

stopping the driving of the drilling rod when the taphole depthaccording to the position detection becomes equal to or deeper than aset value and the detected pressure becomes equal to or lower than alower limit set value for detecting that the taphole has beenperforated;

stopping the driving but maintaining the rotation when, during theforward driving of the drilling rod, said detected pressure reaches anupper limit set value beyond which buckling may occur;

resuming the driving when said detected pressure falls to a lower limitset value or below;

further, maintaining the impact when, during the forward driving of thedrilling rod, said detected pressure is equal to or higher than a setvalue to commence the impact; and

stopping the impact when said detected pressure is lower than said setvalue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) is a flowchart for automatic driving control according to thecontrol method of the present invention.

FIG. 1(b) is a graph showing the relationship between the load andhydraulic load detection according to the automatic driving controlshown in FIG. 1(a).

FIG. 2(a) is a flowchart for automatic impact control according to thecontrol method of the present invention.

FIG. 2(b) is a graph showing the relationship between the load andhydraulic load detection according to the automatic impact control shownin FIG. 2(a).

FIG. 3 is a flowchart for the control method according to the presentinvention.

FIG. 4 is a general view for a conventional taphole opener.

FIG. 5(a) is a flowchart showing the control of a conventional tapholeopener.

FIG. 5(b) is a flowchart subsequent to the flowchart shown in FIG. 5(a)showing the control of a conventional taphole opener.

THE MOST PREFERRED EMBODIMENT

The present invention is described in detail hereafter while referringto the attached figures.

(1) Automatic Driving Control

FIG. 1(a) is a flowchart for automatic driving control according to thecontrol method of the present invention.

A drilling rod is rotated and driven forward by a feed motor uponcommencement of driving and the hydraulic load of a hydraulic unitdriving the feed motor is detected by a pressure gauge (step 101, seeFIG. 1(b)).

The detected pressure is input to an arithmetic unit and a judgement ismade as to whether the detected pressure A is equal to or higher than anupper limit set value F1 of the driving load (step 102). If the detectedpressure A is lower than the upper limit set value F1, then the drivingload does not exceed the value to cause buckling and therefore thedrilling rod maintains rotation and is driven forward through therepetition of steps 101 and 102.

If the detected pressure A exceeds the upper limit set value F1, thedriving load is in a range to possibly cause buckling and therefore thefeed motor is stopped to stop the forward driving of the drilling rod,or the drilling rod is driven backward if the situation so requires(step 103).

The hydraulic load is detected while the forward driving of the drillingrod is suspended but its rotation is maintained (step 104, see FIG.1(b)), and a judgement is made as to whether the detected pressure A isequal to or lower than a lower limit set value F2 (step 105). If thedetected pressure A is equal to or lower than the lower limit set valueF2, the control flow returns to steps 101 and 102 and the drilling rodis driven forward while maintaining the rotation.

The reason why the lower limit set value F2 is set to lower than the setvalue F1 is to drive the drilling rod forward at a driving load notlikely to cause buckling by returning to steps 101 and 102.

When the detected pressure A exceeds the set value F2, step 104 todetect the hydraulic load and step 105 to judge whether the detectedpressure A is equal to or lower than the set value F2 are repeated onceagain. Then, if the detected pressure A is brought to be equal to orlower than the set value F2 by the rotation of the drilling rod, thedriving is commenced by returning to steps 101 and 102.

By the steps described above, the driving load is detected and, when theload reaches the upper limit set value F1 beyond which buckling mayoccur, the forward driving is suspended and only the rotation isretained, and, when the driving load falls to the lower limit set valueF2 or below, the forward driving is resumed. The above measures preventan excessive driving action to cause bucking of the drilling rod fromoccurring.

(2) Automatic Impact Control

FIG. 2(a) is a flowchart for automatic impact control according to thecontrol method of the present invention.

When impacts are given, a drilling rod hits a plugging material in ataphole, driven by an impactor. The hydraulic load in this condition isdetected (step 111, see FIG. 2(b)).

The detected pressure is input to an arithmetic unit and a judgement ismade as to whether the detected pressure A is equal to or lower than aset value D1 (D2, in the case of reverse impacts) to commence theimpacts (step 112). If the detected pressure A is equal to or higherthan the set value D1 (D2), the impacts are effectively done and do nothit idly, and therefore the impacts are maintained by returning to steps111 and 112.

If the detected pressure A falls to lower than the set value D1 (D2),the impacts are not effectively done and possibly hit idly, andtherefore the impacts are suspended (step 113). After that, the impactsare resumed when the detected pressure A recovers. This control preventsthe impactor from idle hitting.

(3) Detection of Taphole Depth

FIG. 3 is a flowchart for the control method according to the presentinvention. Upon commencement of a taphole opening operation, a drillingrod is rotated and driven forward by a feed motor, and the hydraulicload of a hydraulic unit driving the feed motor is detected with apressure gauge (step 131).

The detected pressure is input to an arithmetic unit and a judgement ismade as to whether the detected pressure A is equal to or lower than anupper limit set value P1 (step 132). If the detected pressure A is equalto or lower than the upper limit set value P1, the tip of the drillingrod has not yet reached a plugging material in a taphole and then, thecontrol flow returns to steps 131 and 132 and the drilling rod maintainsrotation and is driven forward. The rod is driven until the tip of therod hits the plugging material in the taphole by, repeating steps 131and 132.

When the rod tip hits the taphole plugging material during the forwarddriving, the detected pressure A exceeds the upper limit set value P1and, at that time, the value of position detection is set to zero (step133), position detection is commenced from this position, and the depthof the taphole is calculated. The drilling rod is driven forward whilethe automatic driving control, under steps 101 to 105, and the automaticforward impact control, under steps 111 and 112, are carried out asdescribed above in parallel with the position detection. While thedrilling rod thus advances, a calculation is made as to whether thedetected position is at or beyond a set position (step 134) and, at thesame time, the hydraulic load is detected and another calculation ismade as to whether the detected pressure A is equal to or lower than alower limit set value P2 (step 135).

When the detected position reaches to or beyond the set position in step134 and the detected pressure A becomes equal to or lower than the lowerlimit set value P2, by the drop of the detected pressure A resultingfrom the perforation of the tip of the drilling rod through the tapholein step 135, the taphole depth is determined by an AND circuit 136 andboth the driving and forward impacts of the drilling rod are stopped.After this, the drilling rod undergoes a retreating action to beextracted from the taphole and is driven backward under automaticreverse impact control.

INDUSTRIAL APPLICABILITY

By the driving control of the present invention, the buckling of adrilling rod can be reliably avoided and the time required for tapholeopening work can be reduced since an excessive driving force possiblycausing buckling is automatically prevented from occurring.

Further, damage to the equipment can be reduced and the service life canbe extended since the equipment is automatically and reliably preventedfrom idle hitting. In addition, workers can be liberated from a foulenvironment since remote operation is made possible through theautomation of taphole opening work.

What is claimed is:
 1. An automatic control method for a hydraulictaphole opener for opening a taphole by giving impact and rotation to adrill unit holding a drilling rod and driving the drill unit forward andbackward by a hydraulically driven feed motor, which method comprisesthe steps of: detecting the driving load in the form of detectedhydraulic pressure; stopping the driving but maintaining the rotationwhen said detected pressure reaches an upper limit set value beyondwhich buckling may occur; and resuming the driving when said detectedpressure falls to a lower limit set value or below.
 2. An automaticcontrol method for a hydraulic taphole opener for opening a taphole bygiving impact and rotation to a drill unit holding a drilling rod anddriving the drill unit forward and backward by a hydraulically drivenfeed motor, which method comprises the steps of: detecting the drivingload in the form of detected hydraulic pressure; maintaining the impactwhen said detected pressure is equal to or higher than a set value tocommence the impact; and stopping the impact when said detected pressureis lower than said set value.
 3. An automatic control method for ahydraulic taphole opener for opening a taphole by giving impact androtation to a drill unit holding a drilling rod and driving the drillunit forward and backward by a hydraulically driven feed motor, whichmethod comprises the steps of: detecting the driving load in the form ofdetected pressure; setting the count of position detection to zero whenthe detected pressure exceeds an upper limit set value for detectingthat the drill unit has reached a plugging material in the taphole,commencing position detection from this position, and calculating thedepth of the taphole; stopping the driving of the drilling rod when thetaphole depth according to the position detection becomes equal to ordeeper than a set value and the detected pressure becomes equal to orlower than a lower limit set value for detecting that the taphole hasbeen perforated; stopping the driving but maintaining the rotation when,during the forward driving of the drilling rod, said detected pressurereaches an upper limit set value beyond which buckling may occur; andresuming the driving when said detected pressure falls to a lower limitset value or below.
 4. An automatic control method for a hydraulictaphole opener for opening a taphole by giving impact and rotation to adrill unit holding a drilling rod and driving the drill unit forward andbackward by a hydraulically driven feed motor, which method comprisesthe steps of: detecting the driving load in the form of detectedpressure; setting the count of position detection to zero when thedetected pressure exceeds an upper limit set value for detecting thatthe drill unit has reached a plugging material in the taphole,commencing position detection from this position, and calculating thedepth of the taphole; stopping the driving of the drilling rod when thetaphole depth according to the position detection becomes equal to ordeeper than a set value and the detected pressure becomes equal to orlower than a lower limit set value for detecting that the taphole hasbeen perforated; maintaining the impact when, during the forward drivingof the drilling rod, said detected pressure is equal to or higher than aset value to commence the impacts; and stopping the impact when saiddetected pressure is lower than said set value.
 5. An automatic controlmethod for a hydraulic taphole opener for opening a taphole by givingimpact and rotation to a drill unit holding a drilling rod and drivingthe drill unit forward and backward by a hydraulically driven feedmotor, which method comprises the steps of: detecting the driving loadin the form of detected pressure; setting the count of positiondetection to zero when the detected pressure exceeds an upper limit setvalue for detecting that the drill unit has reached a plugging materialin the taphole, commencing position detection from this position, andcalculating the depth of the taphole; stopping the driving of thedrilling rod when the taphole depth according to the position detectionbecomes equal to or deeper than a set value and the detected pressurebecomes equal to or lower than a lower limit set value for detectingthat the taphole has been perforated; stopping the driving butmaintaining the rotation when, during the forward driving of thedrilling rod, said detected pressure reaches an upper limit set valuebeyond which buckling may occur; resuming the driving when said detectedpressure falls to a lower limit set value or below; further, maintainingthe impact when, during the forward driving of the drilling rod, saiddetected pressure is equal to or higher than a set value to commence theimpact; and stopping the impact when said detected pressure is lowerthan said set value.